Steroid esters and method of making same



STEROID ESTERS AND METHOD OF MAKING SAME Virgil W. Gash, Dayton, Ohio,assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation ofDelaware No Drawing. Application November 18, 1955 Serial No. 547,847

12 Claims. (Cl. 260397.4)

This invention is directed to new steroid compounds, and to a method ofpreparing such compounds.

The new steroid compounds of my invention are acylsalicyloxy substitutedsteroids, specifically, the acylsalicyloxy substituted cyclopentano10,13 dimethylpolyhydrophenauthrenes of the pregnane-ZO-one series. Suchcompounds combine the therapeutic properties of the steroids with thoseof the acyl salicylates.

The acylsalicyloxy substituted streoids of my invention can berepresented by the general structure:

21(i7Ha 200: CH3 12 I in which the mono-valent radical in the bracketsisa cyclopentano-l0,13-dimethylpolyhydrophenanthrene radi-t cal of thepregnane-ZO-one series. The pregnane-ZO-one series is considered toinclude both saturated and um saturated cycloaliphatic steroids of theabove structure, provided that there is no aromatic unsaturation. Thepregnane-ZO-one series include streoids that are hydrocarbon except forthe 20-keto group, as Well as compounds containing substituents such ashydroxyl, oxo and halogen groups; for example, the steroids can have a3- or ll-keto group, a 3, 11, 17 or 21 hydroxyl group, or a 9-oz-flllrO- or 9-a-chloro-group. The steroids of the pregnane-20-oneseries can contain various ester or alkoxy substituents in place of thehydroxyl groups; of course, in my new compounds there is at least oneacylsalicyloxy group substituted on the steroid. There can be one or twodouble bonds in the phenanthrene rings. The hydroxyl group of thesalicyloxy radical is substituted by an acyl group (RCO in the aboveformula), such as an aliphatic acyl group of 2 to 8 carbon atoms (R'representing an alkyl group), the acetyl group being preferred.

My preferred compounds are the o-acylsalicylic acidesters of thosesteroids of the structure:

' United States Patent a 2,857,404 Patented Oct. 21, 1 958 in which Y isselected from the group consisting of in which R is selected from thegroups consisting of ''CH2 CHOH, and CHOR"", and in which R" is selectedfrom the group consisting of acyl and alkyl groups; in which R isselected from the groups consisting of hydrogen, alkyl and acyl groups;in which R" is selected from the group consisting of H, OH, OR and inwhich R is selected from the group consisting of acyl and alkyl groups;in which R is selected from the group consisting of H, -OH, acyloxy, andalkoxy; and in which X is selected from the group consisting of Cl, F,or H; and in which at least one of R and R is hydrogen, therebypermitting the acylsalicylic acid ester linkage to be formed, such anacylsalicylic acid ester group being attached to at least one of the 3and 21-positions of the steroid. Some examples of the new compounds ofmy invention are A -pregnene-3,21diol-l1,20-dione 21-(0-acetylsalicylate) A -pregnene-17a,21-diol-3,11,20-trione17-acetate,21-(O-acetylsalicylate), pregnane-3,17a-diol- 20-one3-(O-acetylsalicylate), pregnane-3,l7a-diol-11,20- dione3-(O-acetylsalicylate), A -pregnene-3,17a,21-triol- 11,20-dione3,2l-di-(O-acetylsalicylate), pregnane-3,11- diol-ZO-one3-(O-pentanoylsalicylate), A -pregnene-3-ol- 20-one3-(O-acetylsalicylate), A -pregnadiene-11,17,21- triol-3,20-dioneZI-(O-acetylsalicylate), A -pregnadiene- 17,21-diol3,11,20-trioneZI-(O-acetylsalicylate), A

pregnadiene-17,21-diol-3,20-di0ne 21-( O-acetylsalicylate) Y A-pregnadiene-21-ol-3,20-dione 21-(O-acetylsalicylate), cortisone21-(O-propionylsalicylate), cortisone 21-(0- butyrylsalicylate),cortisone 21-(O-caproylsalicylate), and cortisone21-(O-octanoylsalicylate). Especially valuable compounds are theO-acetylsalicylates of the cortiin which R is selected from CH CO, andCHOH, R is H or OH, and X is Cl, F, or H; examples of these particularcompounds are corticosterone 21- (O-acetylsalicylate),17-hydroxycorticosterone 21-(0- acetylsalicylate),ll-desoxycorticosterone ZI-(O-acetylsalicylate), 17hydroxydehydrocorticosterone 21 -(O- acetylsalicylate),9a-fluoro-17-hydroxycorticosterone 21- (O-acetylsalicylate'), and9a-chloro-17-hydroxycorticosterone ZI-(O-acetylsalicylate). As can beseen from the and Zl-hydroxyl groups.

The new compounds of "my invention have valuable therapeutic andanalgesic properties. BpthI thejacetyl salicylates and certain steroids,e. g., cortisone, are known to have therapeutic activity towardrheumatoid arthritis. It has now been discovered thatcortisone:21-O-acetylsalicylate has greatly enhanced activity comparedto cortisone in reducing, edema and swellingin artificially inflamedmammalian joints. This greatly increased activity shows that thecombination of the two reactive groups in one compound produces asynergistic'effect, rather than a mere additive eitect of the twocompounds. Moreover, the presence of the O-acetyl-salicyloxy group, evenin comparatively inactive steroid compounds, such as pregnenolone, makesthe compounds considerably more active, as shown by theanti-inflammatory action of pregnenolone '3-(O-acetylsalicylate) intests with rats. The cause for the increased activity of these compoundsis not clear; perhaps the steroid aids in transporting theO-acetylsalicylate to the proper location for therapeutic action; orperhaps esterification with the O-acetylsalicylic acid. somehow.activates the steroid compound itself, or aids in transporting thesteroid. However, regardless of the mechanism, it is clear thatesterification of inactive steroids of the pregnane-ZO-one series withan O-acylsalicyclic acid produces active compounds, and suchesterificationof active steroids of thefpregnane-ZO-oneseries-producesmore active, compounds.

While some of the members of my new class of chemical compoundsmay existin more than one sterioisomeric.

form, and-it-may be recognized. thatzsome isomers havegreatercortisone-like activity than others, all of theisomeric forms. of my newclass of compounds are novel and within tliescope ofithe'presentinvention.

My. method. for-producing-my. new compounds involves theesterificationof a cyclopentano-1.0,13-dimethylpolyhydrophenanthreneofthe;pregnane-20-one series ;contain-.

ing atleast. one. esterifiable hydroxyl' group by. treating thesaidphenanthrene with an Q-acylsalicyloyl halideor an O-acylsalicylicacidanhydride. The acyl group blocks the hydroxyl groupfof thesalicyloxyl'halide so that it cannot take part in the reaction; any acylgroup will work, although the acetyl group is preferred. Asesterifyingreactantthe acylsalicyloyl chlorides are'preferred, although thebromides can also be used. It is also possible to use an O-acylsalicylicanhydn'de although these anhydrides are not as readily avail'ableas .theacid halides. The reaction conditions'can be varied :considerably, buttemperatures in the range of C. to room-temperature or 25 C. areordinarily used; with some steroids low temperaturesarepreferably inordertoravoid degradation. The reaction is conducted in an organicsolvent, suchas pyridine,

pyridine and ether, ether, benzene, chloroform, etc. The

time of the reaction can vary greatly, e. g., from a few minutes totwodays. A basic material is usually included in the reaction mixture toneutralize the acid which is liberated in the reaction. Such abasicsubstance, e. g., pyridine, is desirable when esterifying-some steroids,e. g., cortisone, in order to obtain good'yield, as in the absence ofsuch a base the liberated acid would tend to degrade the steroid sidechain. With other-steroids,.e. g. pregnenolone, the reaction can beconducted with no. 'base, or with sodium bicarbonate or a stronger base,although an organic amine such as pyridine is still preferred. The pro-After 5 minutes, the mixture was diluted with water and filtered,yielding 0.71 gram ofcortisone 21-acetylsal1cylate,

M. P. 227-230 C., a 56 percent yield. The product was recrystallizedfrom methanol, M. P. 226-230 C. It is clear that the esterificationtakes place on the 2l-hydroxyl group, as the 17-a-hydroxyl group is wellknown to be unreactive, requiring special procedures for esterification.The compoundcan also be designated as'A -pregnene-l7w 7 21-diol-3,11,20-trione ZI-(O-acetylsalicylat'e).

' EXAMPLE. 2

. of O-acetylsalicyloyl. chloride, and the resulting solution was keptat 5 C. for 2 days. Dilution with water followed by filtration andwashing with bicarbonate solution gave 3.0 grams of dried product, M. P.160-168" C., a 99 percent yield in. the form of-small white needles. Tworecrystallizations raised the, M. P. to 174176 C. The infrared; spectrumshowed carbonyl absorption at 5.71 4 (acetate-),f5.85u (salicyloyl), and5.91 (C keto grZollP).

Analysis. flca cjdgfor (3 511 0 (2, 75.49; H, 8.00.

f Found: C, 75.88; H, 8.42. I p

[04 (CHCl +22-.3, m =.106.7, and ultraviolet.

absorption 0m (ethanol) at 227.5 m

The compound had significant anti-inflammatory action in the Wintersmodification of the Selye inflammation test with rats, having a t at 48hours of 3.26, and at 24 hours, of 3.55. As pregnenolone does not havesignificant anti-inflammatory activity, it was surprising to find thatthe acetylsalicylate of pregnenolone, i. e., A -pregnene-3fi-ol-20-one3-(O-acetylsalicylate), does have such activity.

EXAMPLE 3 Cortisone, 034 gram 0.000943 mol) was dissolved in a solutionof. 15nd. dry CHCl and 2 ml. dry'pyridine.

Freshly distilled acetylsalicyloyl chloride (B. P. 77- 79/04 mm. Hg),0.2 gram (.001 mol) was added and the solution was brought to a boil 0nthe-steam bath, then wasallowed to stand overnight at room temperature.Water was added, .1-ml., and the solution was allowed to evaporateatroom' temperature. The residue was taken up in etherbenzene solutionand washed successively with dilute portions can be varied from a slightexcess of ester-ifying agent over the stoichiometric amount required to"este rify the desired number of hydroxyl groups, up to a much. largerexcess, e. g., l00'p'ercent.

HCl; water, bicarbonate solution'and water. The solvents were removedand the residue was recrystallized from ethanol to give 0.1 gram ofcortisone acetylsalicylate. Recrystallized from ethanol, M. P. 228230 C.

Analysis.Calcd. for C H O C, 68.95; H, 6.56. Found: C, 68.71; H, 7.01.

The compound showed the following anti-inflammatory activity the Wintersmodification of the Selye inflamma.tion test with'rats having silvernitrate inflamed'ankles.

The dosages were 25 and 50 mg./kg. subcutaneously twice daily, while thecontrols were 50 mg. of cortisone'acetate-twicedaily, one controlsubcutaneously and the other orally;

Talile l Ht Dose,'mg./kg.

24 hours 4s hours so 5; 475 5. to V 25 4. 595 3. 223 50 (Control, SC) 2.59 2. 73 50 (Control, oral) 2. 42 3. 11

The Winters modification of the Selye inflammation test is a commonmethod of determining anti-inflammatory activity. The values for t inTable I are statistical values showing differences between treated andnontreated groups of animals. It is sometimes referred to as Students ttest.

It can readily be seen that cortisone acetylsalicylate has a significantanti-inflammatory effect, being more than double that of the control.

A general review of methods of bioassay of steroid hormones, includingsome anti-inflammatory tests, can be found in Physiological Reviews, 34,138-166 (1954).

EXAMPLE 4 A3,; 232 my having an extinction coefiicient of e=26,780 andlog Analysis.-Calcd. for C H O C, 68.95; H, 6.56. Found: C, 68.39; H,6.61.

The compound was recrystallized from acetone, M. P. 230-231 C.

Analysis.-Found: C, 69.26; H, 6.46.

EXAMPLE 5 A solution of 0.50 gram (1.5 millimoles) ofdesoxycorticosterone in 4 ml. of dry pyridine was cooled in an ice bathand treated with 0.32 gram (1.6 millimoles) of acetylsalicyloylchloride. After one hour at C. and 15 minutes at 25 C., the solution wasdiluted with excess water and extracted with ether. After washing withsodium bicarbonate solution and water, the ether solution was strippedleaving a colorless, noncrystalline residue soluble in most organicsolvents. The product was dissolved in methanol and precipitated bydilution with water to yield 0.65 gram of a nearly white, amorphouspowder having no definite melting point, which was desoxycorticosterone21 acetylsalicylate. Infrared analysis showed (1,,8-11115311113l6dcarbonyl at 6.03;; and 6.21;. (A -3-keto); other carbonyl absorption at5.7/.!. (acetate) and 5.84 (C-20 carbonyl). There was no hydroxylabsorption at 2.88 such as is characteristic of the starting material.The infrared spectrum was strikingly similar to that for cortisoneZl-acetylsalicylate in the carbonyl frequency region.

The desoxycorticosterone 21-acetylsalicylate structure, i. e., A-pregnene-2l-ol-3,20-dione 21-(O-acetylsalicylate), was furtherconfirmed by ultraviolet analysis,

X3; 235 mp an extinction coeflicient e=24,130, and log 2:438; theultraviolet curve was almost identical to that for cortisone21-acetylsalicylate in Example 4.

Analysis.Calcd. for C l-1 0 C, 73.15; H, 7.37. Found: C, 73.29; H, 7.46.

The above reaction was also carried out in pyridineether solution toyield the same product.

The O-acetylsalicyloyl chloride for the above procedures can be preparedby chlorinating acetylsalicylic acid with phosphorous pentachloride togive a product boiling at 90-92 C./ 0.4 mm. Hg.

While my new compounds in the examples above are prepared byesterification procedures, it will be realized that my compounds canalso be prepared by other methods. For example, a 21-halosteroid can bereacted with a metal salt of an acylsalicylic acid.

The following table compares the activity of some of the steroidacylsalicylic acid esters of my invention to that of cortisone inreducing inflammation and edema in yeast injected rat ankles. Alldosages were given by subcutaneous injection.

Cortisone 21-(0-acetysalicyl3te) Desoxycorticosterone2l-(O-acetylsalicylate) Pregnenolone 3-(0-acetylsalieylate) From theabove table it is apparent that the O-acetyl salicylic acid ester groupmakes cortisone four times as active in the test, and gives the othercompounds activity equal to that of cortisone. 4

The present invention provides the acylsalicylic acid esters of certainsteroids as a new class of chemical'com pounds having valuablepharmaceutical properties. The invention also provides a convenientmethod of these new steroid acylsalicylic acid esters.

I claim:

1. As new compounds, the 2l-O-acylsa1icyclic acid esters of steroidsselected from the group consisting of steroids of the formula:

CHiOH and the same containing a 1-2 double bond, in which R is selectedfrom the group consisting of CH:, CO and CHOH; R is selected from thegroup consisting of H and OH; and X is selected from the groupconsisting of Cl, F, and -H, and in which acyl is an alkyl CO- group of2 to 8 carbon atoms.

2. The compounds of claim 1 in which the O-acylsalicylic acid isO-acetylsalicylic acid.

3. As compounds, the 21-O-acetylsalicylates of steroids selected fromthe group consisting of 17-hydroxycorticosterone,17-hydroxy-ll-dehydrocorticosterone, ll-dehydrocorticosterone,corticosterone, 17-hydroxy-1l-desoxycorticosterone,ll-desoxycorticosterone, and the A -derivatives of the foregoing.

4. As a new compound, A -pregnene-17a,21-diol-3,1l, 20-trione21-(O-acety1salicylate).

5. As a new compound, A -pregnene-3firol-20-one 3- (O-acetylsalicylate)6. As a new compound, M-pregnene-Z1-ol-3,20-dione21-(O-acetylsalicylate) 7. The method of obtaining an acylsalicylic acidester of a hydroxyl-containing cycloaliphatic cyclopentano-IO,13dimethylpolyhydrophenanthrene of the preguane 20- one series whichcomprises esterifying said phenanthrene by treatment with a memberselected from the group consisting of acylsalicyloyl chlorides,acylsalicyloyl bromides, and acylsalicylic anhydrides in which acylrepresents an alkyl-CO- group of 2 to 8 carbon atoms and in which thesaid phenanthrene is selected from the group consisting of steroids ofthe formula:

preparing 7 and the same containing a; 1:42 double bond, in which R issele cted irom thegrolip "consisting of -CH,;, CO and -,CHOH; R isselectedfrom the group consisting of-- Hahd --OH; and X is selected fromthe group consisting' of Cl, -F and H.

8. The method ofc1aim'7 in which the said phenanthrene isesterified-with Oacetylsalicyloyl chloride in Organic solventin thepresen'eegf'an or anic amine.

9. The method of claim 7 in which said phenanthrene is 'esterified withO-gcetyisalicyloyl chloride in pyridine sohientlat a temperature between'Of'C. and 25 C.

'10; The methodofcla iin Tin-which acyl represents ac'etyl. t s

11, The method of, obtaining 2 1 acyl'salicyloxy steroids wh es l i an yi wi of 2 to 8 carbon atoms whichsomprise reactinge steroid selectedfrom the group consisting}; of 17 hydrqiycorticosterone, 17-hydroxy 11dehydrocorticosterongvl l dehydrocorticosterone, corticosterone, 17-hydroxy-1bdesoxycorticosterone, II-desdXYcOiticOS'tiOrie and the A-de'r'ivati'ves of the foregoingwitha member selected from the" groupconsisting.of'gcylsalicyloyl chlorides acylaliyIbYl' bromides',anda'cyl'salicylie anhydr'ides'in which acylhas the meaning s'et forthabove.

12. The method of 'prepa'ringflcortisone ZI-(O-acetylsalicylate) twhichcomprises reacting cortisone with O- acetylslicyloyl: chl'di'id'e.

References Cited inthefileof this patent UNITED STATES PATENTSReichstein Dec. 19, 1939 Barseie Oct. 12, 1 954 OTHER: REFERENCES Fieseret aL: Na tilral Products Related to Phenanthrene, 3rd ed., pp. 424-26(1949).

1. AS NEW COMPOUNDS, THE 21-O-ACYLASLICYCLIC ACID ESTERS OF STEROIDSSELECTED FROM THE GROUP CONSISTING OF STEROIDS OF THE FORMULA: